From mboxrd@z Thu Jan  1 00:00:00 1970
From: jianchao.w.wang@oracle.com (jianchao.wang)
Date: Mon, 16 Jul 2018 16:52:39 +0800
Subject: [PATCHv4 1/4] nvme: Sync request queues on reset
In-Reply-To: <20180713205609.19701-2-keith.busch@intel.com>
References: <20180713205609.19701-1-keith.busch@intel.com>
 <20180713205609.19701-2-keith.busch@intel.com>
Message-ID: <9bd80570-5b7d-c093-ffbb-a8fbcaa58db0@oracle.com>

Hi Keith

On 07/14/2018 04:56 AM, Keith Busch wrote:
> This patch fixes races that occur with simultaneous controller
> resets by synchronizing request queues prior to initializing the
> controller. Withouth this, a thread may attempt disabling a controller
> at the same time as we're trying to enable it.

This issue is due to the previous blk-mq timeout mechanism will hold
all the timed out requests, then nvme_dev_disable cannot grab these requests
and when it returns, the blk_mq_timeout_work could be still running.
But after commit 12f5b9314545 ("blk-mq: Remove generation seqeunce"),
nvme_dev_disble have been able to grab all the requests and when it returns,
there will be no any requests in blk_mq_timeout_work so nvme_dev_disable will
not be invoked multiple times.
So this patch should be unnecessary. :)

Thanks
Jianchao